“Openness, connection, a sense of purpose combined with humility — these are what America desperately needs today," the group wrote.
The impeachment managers continued to make their case to the Senate for removing President Donald Trump from office.
The Democratic presidential dropout said she also admires Warren and Sanders, but suggested they don't need her help "right now."
At least 11 U.S. service members were airlifted out of Iraq following Iran's missile strikes on the Ain al-Asad air base.
It's the first time the organization's political action committee has backed someone running against the Republican senator since 2008.
The Vermont senator distanced himself from the piece, which was written by one of his high-profile supporters and promoted by his campaign.